1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor, and more particularly, to a multilayer ceramic capacitor having a high level of reliability and a low crack occurrence rate by reducing stress acting on the multilayer ceramic capacitor.
2. Description of the Related Art
In general, electronic components using a ceramic material, such as capacitors, inductors, piezoelectric devices, varistors or thermistors, include a ceramic body formed of a ceramic material, internal electrodes provided inside the ceramic body, and external electrodes installed on the surface of the ceramic body.
Multilayer ceramic capacitors among such ceramic electronic components include a plurality of laminated dielectric layers, internal electrodes interleaved with the dielectric layers, and external electrodes electrically connected to the internal electrodes.
Multilayer ceramic capacitors are being widely used as a part of mobile communications devices, such as computers, personal digital assistants (PDA) and mobile phones, due to their small size, high capacity and ease of mounting.
Recently, as electronic products have become compact and multi-functional, chip components have also tended to become compact and highly functional. Following this trend, a multilayer ceramic capacitor is required to be smaller than ever before, but to have a high capacity.
As for a general method of manufacturing a multilayer ceramic capacitor, ceramic green sheets are manufactured and a conductive paste is printed on the ceramic green sheets to thereby form internal electrode layers. Tens to hundreds of such ceramic green sheets, provided with the internal electrode layers, are then laminated to thereby produce a green ceramic laminate. Thereafter, the green ceramic laminate is pressed at high pressure and high temperature and subsequently cut into green chips. Thereafter, the green chip is subjected to plasticizing, firing and polishing processes, and external electrodes are then formed thereon, thereby completing a multilayer ceramic capacitor.
Typically, the internal electrodes, formed of metal, shrink and expand easily as compared to ceramic materials. Thus, stress caused by this difference in thermal expansion coefficient may act on the ceramic laminate, thereby causing cracks.
The multilayer ceramic capacitor is used while mounted on a wiring board. In this case, the external electrodes of the multilayer ceramic capacitor are electrically connected to the wiring board by soldering and a conductive land on the wiring board. When the multilayer ceramic capacitor is mounted on the wiring board by using soldering, or when the wiring board mounted with the multilayer ceramic capacitor undergoes a cutting process, thermal impact and shear stress are applied to the multilayer ceramic capacitor. Such thermal impact and shear stress may cause cracks in the multilayer ceramic capacitor.
As the multilayer ceramic capacitor has recently become smaller in size and higher in capacitance, many attempts have been made to manufacture a thinner and multilayer ceramic body. However, as the ceramic body has become thinner and multilayered, a crack occurrence rate has increased. Therefore, there is an increasing need for preventing this increase in the crack occurrence rate therein.